I was able to find a few things in searching, but nothing quite like my problems.
this all started about 2-3 months ago, my car misfires while driving, but only in certain rpm ranges, and the gear im in at the time also seems to play a part in it(atx by the way). while in drive with o/d on it does it all the time, when i turn o/d off it will only do it from like 2200 to around 3100 rpm's except when im starting from a stop, then it does it from idle all the way to 3100. if i have it in 2nd it will only do it til about 2400 or so.

I get a flashing CEL all the time, and from my understanding when it flashes it signals an active multiple cylinder misfire. ive changed my plugs and wires, havent done the coil pack yet but i did test it and everything was within specs that i got from here and from my haynes. as a matter of fact im on my 4th set of plugs in the last 3 months. everytime i change them, it helps a little but only for about 300 miles or less.

someone in a previous post had mentioned to someone else that a plugged up catalytic convertor could cause misfire problems, but it didnt make much sense to me. so what im wondering is if since it is an older car, if some part of my electrical system could be going bad, and the spark plugs arent getting enough juice to produce a full spark? or could it actually be the cat like someone else said?

TIA, sorry for the length.

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I would test the coilpack most def. New plugs gapped at .044 and yea....the cat could be clogged up enough to cause a hesitation like that imo.

Compression test might tell you that a cylinder is weak and is losing compression. I don't know what else to say really. Maybe a crappy injector or something.

I eat emo kids for breakfast

1995 Eagle Talon (SOLD)
72' SuperBeetle
72' Standard Beetle
56' Deluxe Beetle

O2 sensor
timing belt
sticking injector

i thought of the O2 sensor, but i wasnt sure. i thought maybe that it was getting wrong readings and the ECU was adjusting the fuel, causing it to run to rich, but i dont know. I just did the timing belt about 6k miles ago, so i doubt its that. as far as the injectors sticking, is there anyway to test this or am i pretty much limited to trying a different set?

Thanks for the responces so far. Keep em' commin!
Edit: forgot to add before that when its misfiring, alot of the times it sounds like when you set off an m-80 in side a aluminum can.

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To check the injectors, you can take a long screwdriver and listen to them at idle to see if one isn't ticking like the others. EDIT: If you suspect one is sticking, you can disconnect the harness to it and see if the symptoms change. If they don't chances are you still have fuel flowing into the engine (sticking).

The ECU is designed to go to a default map when the O2 takes a dump, running overly rich to prevent leaning out and nuking shit, but I've never had misfire as a result.

It doesn't matter how far recently you did timing. My belt jumped a couple teeth on me less than a month after I put the engine back together. If the tensioner gets "tired," it can allow the timing to gradually slip until you lose compression and the engine will not fire. Also, keep in mind that most people whose timing is off by a tooth or so usually post up asking why they have a shitty idle right away...

-"Easy Mac"
05 Mazda RX-8 (RR8 #88)
99 Eclipse RS 398whp & 372lb-ft

the misfire started about 8 months after the timing belt change.

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Check your timing. I bet it's off a tooth or 2. Mine would misfire in the upper RPM range because of the stupid timing.

-"Easy Mac"
05 Mazda RX-8 (RR8 #88)
99 Eclipse RS 398whp & 372lb-ft

about how much should it cost for me to take it somewhere to have the timing done. i dont have the facilities or the proper tools right now to be able to do it myself.

and when you say you had problems in the upper ranges, my problems are in the lower ranges, lower than 3000, so would you still think a possible timing problem. it doesnt do it at all above 3000, unless i'm in drive with the o/d on, then it does it all through the rpm range.

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Yeah I still think it's timing related. If you've checked all the other usual suspects, then timing is left. I don't know how much they would charge you honestly. I don't really trust most places to figure out how to get timing correct on a 2gnt.

-"Easy Mac"
05 Mazda RX-8 (RR8 #88)
99 Eclipse RS 398whp & 372lb-ft

well, thanks for the advice so far. if it would stop raining here i would check out the injectors like DR suggested, but i guess it'll wait. so once i get everything checked out ill let you guys know what i find.

and if anyone else has anything to add, i would be most appreciative.

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i guess i should also mention, since i forgot to earlier. everytime i have changed the plugs in the past 3 months, they have been almost completly black. which to my knowledge, is a sign of un-burned gasoline. and ive changed them every 300-400 miles recently, just because changing them seems to help with the problem, but just for a few days. i dont know if this helps anyone in helping me diagnose the problem, but i figured it couldnt hurt to mention either.

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Sounds like it is load based. In 4th(OD) @ 40 MPH the engine is seeing a greater load than in 3rd @ 40. Hows the air filter look? Has the fuel filter been replaced recently? Ohm out the engine temp sensor. If the sensors resistivity is incorrect it could tell the comp. that it is colder that it really is and make it run richer.

AEM cam gears, .030 over, .020 milled head, Unorthodox UDP, port match intake/head, polished exhaust manifold, e-bay CAI, Magnaflow muffler

1995 GS A/T: Crushed, what started it all
1999 RS M/T: Back to stock
Mazdaspeed6: sold and quazi missed
1999 Eclipse GSX: HX35, waiting for Shep STG3

CLT? sorry for being stupid, but i dont see anything that even resembles CLT in the previous posts.

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so i went today to get the CLT, and my friend that works at advanced went and pulled it for me, it was the larger of the 2 sensors on the neck that their computer is saying is the CLT, and not the smaller lower one. so i get home and go to put it in. have to take the smaller one out to get to the larger one that i got, go to take the larger one out and i have every size open ended wrench, except the one i need, go figure. im gonna go get a wrench tomorrow, but i wanna know if i even have the right part. they both look kinda the same, just one is alot smaller. should i try to locate one of the smaller ones too, while i have it out?

oh, and when i go to listen to the injectors, should i place the tip of the screw driver closer to the fuel rail, or closer to the intake to be able to hear the ticking better?

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????????

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I would change both. That's what I did on my 86 cavy. Advance has them listed as a Temperature Switch/Sender. $14.88. That is the one you need so you can do both.

http://www.partsamerica.com/ProductDetail.aspx?mfrcode=ACD&mfrpartnumber=E1878&parttype=425&ptset=A